A spirometry test is utilized to diagnose asthma. It measures how much air you can inhale and how much and how fast you can exhale. If you’re already receiving treatment for asthma, your doctor may perform this test periodically to see how well your medicines are working and if your symptoms are under control.

Prior to the test, your doctor may advise you to avoid using your inhaler or taking other medications. The test will be administered by a nurse. He or she will give you specific instructions about how to take the test. It is important that you follow these instructions carefully to ensure accurate results.

The test results provide measurements for:

Forced Vital Capacity (FVC). The greatest amount of air you are able to forcefully exhale after taking a deep breath. A number lower than the norm indicates restricted breathing.

Forced Expiratory Volume (FEV-1). This is the amount of air you can exhale in one second. A number lower than normal indicates significant obstruction.